#include "bn.h"

#ifndef WITH_LIBCRYPTO
//FIXME Not checked on threadsafety yet; after checking please remove this line
/* crypto/bn/bn_add.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The license and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution license
 * [including the GNU Public License.]
 */

#include <stdio.h>
#include "openssl_mods.h"
#include "bn_lcl.h"

/* r can == a or b */
int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
	const BIGNUM *tmp;

	bn_check_top(a);
	bn_check_top(b);

	/*  a +  b  a+b
	 *  a + -b  a-b
	 * -a +  b  b-a
	 * -a + -b  -(a+b)
	 */
	if(a->neg ^ b->neg)
	{
		/* only one is negative */
		if(a->neg)
		{
			tmp = a;
			a = b;
			b = tmp;
		}

		/* we are now a - b */

		if(BN_ucmp(a, b) < 0)
		{
			if(!BN_usub(r, b, a)) { return (0); }
			r->neg = 1;
		}
		else
		{
			if(!BN_usub(r, a, b)) { return (0); }
			r->neg = 0;
		}
		return (1);
	}

	if(a->neg)  /* both are neg */
		{ r->neg = 1; }
	else
		{ r->neg = 0; }

	if(!BN_uadd(r, a, b)) { return (0); }
	return (1);
}

/* unsigned add of b to a, r must be large enough */
int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
	register int i;
	int max, min;
	BN_ULONG *ap, *bp, *rp, carry, t1;
	const BIGNUM *tmp;

	bn_check_top(a);
	bn_check_top(b);

	if(a->top < b->top)
	{
		tmp = a;
		a = b;
		b = tmp;
	}
	max = a->top;
	min = b->top;

	if(bn_wexpand(r, max + 1) == NULL)
		{ return (0); }

	r->top = max;


	ap = a->d;
	bp = b->d;
	rp = r->d;

	carry = bn_add_words(rp, ap, bp, min);
	rp += min;
	ap += min;
	i = min;

	if(carry)
	{
		while(i < max)
		{
			i++;
			t1 = *(ap++);
			if((*(rp++) = (t1 + 1)&BN_MASK2) >= t1)
			{
				carry = 0;
				break;
			}
		}
		if((i >= max) && carry)
		{
			*(rp++) = 1;
			r->top++;
		}
	}
	if(rp != ap)
	{
		for(; i < max; i++)
			{ *(rp++) = *(ap++); }
	}
	/* memcpy(rp,ap,sizeof(*ap)*(max-i));*/
	return (1);
}

/* unsigned subtraction of b from a, a must be larger than b. */
int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
	int max, min;
	register BN_ULONG t1, t2, *ap, *bp, *rp;
	int i, carry;


	bn_check_top(a);
	bn_check_top(b);

	if(a->top < b->top)  /* hmm... should not be happening */
	{
		return (0);
	}

	max = a->top;
	min = b->top;
	if(bn_wexpand(r, max) == NULL) { return (0); }

	ap = a->d;
	bp = b->d;
	rp = r->d;

#if 1
	carry = 0;
	for(i = 0; i < min; i++)
	{
		t1 = *(ap++);
		t2 = *(bp++);
		if(carry)
		{
			carry = (t1 <= t2);
			t1 = (t1 - t2 - 1)&BN_MASK2;
		}
		else
		{
			carry = (t1 < t2);
			t1 = (t1 - t2)&BN_MASK2;
		}
#if defined(IRIX_CC_BUG) && !defined(LINT)
		int dummy;
		dummy = t1;
#endif
		*(rp++) = t1 & BN_MASK2;
	}
#else
	carry = bn_sub_words(rp, ap, bp, min);
	ap += min;
	bp += min;
	rp += min;
	i = min;
#endif
	if(carry)  /* subtracted */
	{
		while(i < max)
		{
			i++;
			t1 = *(ap++);
			t2 = (t1 - 1)&BN_MASK2;
			*(rp++) = t2;
			if(t1 > t2) { break; }
		}
	}
#if 0
	memcpy(rp, ap, sizeof(*rp) * (max - i));
#else
	if(rp != ap)
	{
		for(;;)
		{
			if(i++ >= max) { break; }
			rp[0] = ap[0];
			if(i++ >= max) { break; }
			rp[1] = ap[1];
			if(i++ >= max) { break; }
			rp[2] = ap[2];
			if(i++ >= max) { break; }
			rp[3] = ap[3];
			rp += 4;
			ap += 4;
		}
	}
#endif

	r->top = max;
	bn_fix_top(r);
	return (1);
}

int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
	int max;
	int add = 0, neg = 0;
	const BIGNUM *tmp;

	bn_check_top(a);
	bn_check_top(b);

	/*  a -  b  a-b
	 *  a - -b  a+b
	 * -a -  b  -(a+b)
	 * -a - -b  b-a
	 */
	if(a->neg)
	{
		if(b->neg)
		{
			tmp = a;
			a = b;
			b = tmp;
		}
		else
		{
			add = 1;
			neg = 1;
		}
	}
	else
	{
		if(b->neg)
		{
			add = 1;
			neg = 0;
		}
	}

	if(add)
	{
		if(!BN_uadd(r, a, b)) { return (0); }
		r->neg = neg;
		return (1);
	}

	/* We are actually doing a - b :-) */

	max = (a->top > b->top) ? a->top : b->top;
	if(bn_wexpand(r, max) == NULL) { return (0); }
	if(BN_ucmp(a, b) < 0)
	{
		if(!BN_usub(r, b, a)) { return (0); }
		r->neg = 1;
	}
	else
	{
		if(!BN_usub(r, a, b)) { return (0); }
		r->neg = 0;
	}
	return (1);
}

#endif
